1. Field of the Invention
The present invention relates to a zoom lens having a reflecting surface that deflects the optical path. The present invention also relates to an image pickup apparatus equipped with such a zoom lens and an image pickup element.
2. Description of the Related Art
Zoom lenses used in image pickup apparatuses such as digital cameras and video cameras are required to have high performance and high zoom ratio and to be made smaller. One of the important factors in achieving a reduction in the size of the image pickup apparatus is the thickness of the zoom lens (i.e. the dimension of the lens system measured along the direction of the axis of light incident thereon from the object side).
In a know type of zoom lens, in order to reduce the thickness of the image pickup apparatus or camera when not in use, the lens system is extended out from the camera body when in use (i.e. when the apparatus is turned on) and received in the camera body when not in use (i.e. when the apparatus is turned off).
However, in this type of zoom lens, the first lens unit is extended greatly out from the body of the image pickup apparatus when the apparatus is turned from off to on. This is disadvantageous in terms of driving time and power consumption.
On the other hand, there is a known zoom lens in which a reflecting member is provided in the first lens unit disposed closest to the object side to deflect the optical path, in order to reduce the operation of the image pickup apparatus performed when it is turned on and to achieve slimming of the apparatus.
There is a known zoom lens including a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a positive refracting power, in which a reflecting member that deflects the optical path is provided in the first lens unit to achieve slimming of the image pickup apparatus with respect to the thickness direction while maintaining a zoom ratio as high as approximately four, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-343622.
There is another known zoom lens including a first lens unit having a negative refracting power, a second lens unit having a negative refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a negative refracting power in which a reflecting member that deflects the optical path is provided in the first lens unit to achieve slimming of the image pickup apparatus with respect to the thickness direction while maintaining a zoom ratio as high as approximately three, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-98962.